"but a single woman may seclude herself with two men":Rav Yehuda cited Rav: They only learned this regarding moral people, but by immoral people, even 10 are also forbidden.And there was an incident in which 10 {immoral men} took her out on a bier {in order to have relations with her}.Rav Yosef said: Know that ten will join together to steal a beam, and will not be ashamed of one another.

Rav said: We lash for seclusion, but do not forbid {Rashi: to her husband; Tosafot: to a kohen} because of seclusion.Rav Ashi said: They only learned this {our gemara: lo amran, which allows greater latitude for Rashi; indeed, Rashi has the girsa of lo amru} about the seclusion of a penuya, but for seclusion of a married woman {we do not lash, for otherwise} we will be slandering her children.Rav said: We lash on not good rumors. For it is stated {I Shmuel 2:24}

At a time that his wife is with him, he may sleep with them in an inn, because his wife is guarding him.A male may seclude himself with his mother and with his daughter, and sleep with them with closeness of flesh {=without clothing}. When they grow up, this one sleeps in his clothes and this one sleeps in her clothes.

Rav Yehuda cited Rav Assi: A man may be secluded with his sister, and may dwell with [his mother and with] his daughter.When I {=Rav Yehuda} said this before Shmuel, he said to me {our gemara makes this a statement, not necessarily said to Shmuel}: It is forbidden to be secluded with all of the forbidden relations in the Torah, and even with an animal.Rava said: A man may seclude himself with two yevamot {that is, married to brothers}; with two rivals {wives of another man}; with a woman and her yevama {sister-in-law; our gemara has mother-in-law}; with a woman and her husband's daughter; and with a woman and a female child who knows the meaning of intercourse, but who does not give herself over to intercourse {since is to young to want to engage in it}.

"When they grow up, this one sleeps in his clothes and this one sleeps in her clothes":And how much? Rav Acha bar Rav Aza cited Rav Ashi: A female child 9 years and a day and a male child 12 years and a day. And some say: A female child 12 years and a day and a male child 13 years and a day.And both this and that is until there is {Yechezkel 16}:

7 I cause thee to increase, even as the growth of the field. And thou didst increase and grow up, and thou camest to excellent beauty: thy breasts were fashioned, and thy hair was grown; yet thou wast naked and bare.

Rafram bar Pappa cited Rav Chisda: They only learned this where she is embarrassed to stand naked, but if she is not embarrassed to stand naked, no.Rava said: They only said this where she is betrothed, but if she is not betrothed, we have no issue with it.

A bachelor should teach children, and a woman should not teach children.Rabbi Eliezer says: Even one whose wife is not with him should not teach children.Rabbi Yehuda says: A bachelor should not graze animals, nor should two bachelors sleep in a single sheet.And the Sages permit.

Anyone who deals with women {as a profession} should not seclude himself with the women.One should not teach his son a profession among the women; One should not teach his son to me a donkey-driver, a camel-driver, a sailor, a wagon-driver, a shopkeeper, or a shepherd, because their professions are professions of robbers.